CN105073307B

CN105073307B - Electroconductive particle, its manufacturing method, the conductive resin composition containing it and electric conductivity coating material

Info

Publication number: CN105073307B
Application number: CN201480016829.9A
Authority: CN
Inventors: 中谷敏雄; 南山伟明; 小池和德
Original assignee: Toyo Aluminum KK
Current assignee: Toyo Aluminum KK
Priority date: 2013-03-28
Filing date: 2014-03-20
Publication date: 2019-04-19
Anticipated expiration: 2034-03-20
Also published as: KR102226109B1; WO2014156978A1; CN105073307A; EP2979781A1; KR20150136121A; JPWO2014156978A1; TW201446970A; EP2979781B1; JP2018076603A; JP6312655B2; EP2979781A4; JP6813519B2; KR20210027541A; US20160055931A1; KR20180132176A; TWI583802B; US10020090B2; KR20210104167A

Abstract

Electroconductive particle of the invention has the metal envelope of the core particle containing aluminium and coating core particle, and metal envelope has the electric conductivity higher than core particle, and metal envelope is 80% or more to the covering rate on the surface of core particle.

Description

Electroconductive particle, its manufacturing method, conductive resin composition and conduction containing it Property coating material

Technical field

The present invention relates to a kind of electroconductive particle, its manufacturing method, contain its conductive resin composition and electric conductivity Coating material.

Background technique

In the past, the conductive resin compositions such as conductive paste, conductive coating paint, conductive adhesive were used for electronics zero The various uses such as part, electronic circuit.As electroconductive stuffing used in such conductive resin composition, it is known to granular Or silver (Ag) particle of sheet, copper (Cu) particle etc..Although there is valuableness however, Ag has very excellent electric conductivity Problem in addition, Cu, due to being oxidized easily, corrosion resistance is lower, therefore there are problems that electric conductivity can not be kept for a long time.

In contrast, Japanese Patent Laid-Open 2008-111175 bulletin (patent document 1), Japanese Patent Laid-Open It is proposed in 2004-52044 bulletin (patent document 2) and Japanese Patent Laid-Open 2006-161081 bulletin (patent document 3) The electroconductive stuffing for thering is the surface of Cu particle to be coated by Ag.The electroconductive stuffing is conductive, corrosion resistance, moisture-proof etc. Excellent feature.But Cu, since specific gravity is larger, when using Cu particle as core particle, there are electroconductive stuffings to exist Sedimentation, operational (easiness of processing) lower problem are easy in conductive resin composition.

As the technology for solving the problems, such as above-mentioned specific gravity, positive exploitation is coated with leading for Ag on the surface of the lesser resin of specific gravity Conductive fillers.But the resin itself due to becoming core particle is without electric conductivity, it is high in order to be obtained in the electroconductive stuffing Electric conductivity, it is necessary to increase the usage amount of Ag, as a result there are problems that manufacturing cost is got higher.

For above-mentioned various problems, the smaller and conductive core particle as cheap, specific gravity can enumerate aluminium (Al) grain Son.Ag is coated on the surface of Al particle for example, disclosing in Japanese Patent Laid-Open 2010-53436 bulletin (patent document 4) Electroconductive stuffing.

Existing technical literature

Patent document 1: Japanese Patent Laid-Open 2008-111175 bulletin

Patent document 2: Japanese Patent Laid-Open 2004-52044 bulletin

Patent document 3: Japanese Patent Laid-Open 2006-161081 bulletin

Patent document 4: Japanese Patent Laid-Open 2010-53436 bulletin

Summary of the invention

Subject to be solved by the invention

However, also clearly being learnt according to the figure disclosed in patent document 4, the electric conductivity disclosed in patent document 4 is filled out Largely there is the part for exposing Al in material.Such electroconductive particle has the possibility that can not play expected sufficient conductivity. In addition, being easy to corrode since the part, maintaining electric conductivity to fill out with being as a result unable to fully if the part for exposing Al largely exists The electric conductivity of material.

The present invention exactly researched and developed in view of above-mentioned status, its purpose is to provide it is a kind of using metal envelope fully by Cover electroconductive particle made of the core particle containing Al, its manufacturing method, conductive resin composition and electric conductivity containing it Coating material.

Means for solving the problems

The inventors of the present invention have carried out various researchs to solve the above-mentioned problems, as a result learn: Al is carried out in aqueous solvent In the case where the plating processing of particle, there are the tendencies of Al particle and etchant vigorous reaction, and there are Al particles also and as molten The tendency of the water vigorous reaction of agent, additionally, there are the tendencies that plating reaction also became over and caused the dissolution of Al particle.Moreover, Since these unnecessary reactions occur, therefore, it is difficult to control the reaction of target, as a result it is difficult to manufacture abundant using metal envelope Ground carries out coating electroconductive particle.In addition, hydrogen can also be generated along with above-mentioned unnecessary reaction by also learning.Manufacturing process In hydrogen generation but also secure context is undesirable.

But the plating processing disclosed in patent document 4 is electroless plating method, is one kind of wet type plating.Make For the method to core particle coated metal, have vacuum vapour deposition, sputtering method, ion plating method, chemical vapor deposition (CVD, ChemicalVaporDeposition) the wet types plating such as the dry types such as method plating, galvanoplastic, electroless plating method.Dry type plating Although the method for applying has the advantages that film can be made, large-scale device is needed, additionally, there are particle is difficult to metal quilt The problem of film equably forms a film.On the other hand, wet type plating, which has, is not necessarily to the large-scale device as dry type plating, And can the coating object such as single treatment a large amount of particle the advantages that.

In view of above-mentioned advantage, the purpose of the inventors of the present invention is: using non-electrolytic plating not using dry type plating On the basis of method, above-described problem is eliminated, thus to obtain coating electroconductive particle is sufficiently carried out using metal envelope.

Moreover, the inventors of the present invention obtain following opinion and research is repeated to electroless plating method: containing in use In the case where the core particle for having Al, used reaction solution is handled by the way that organic solvent and aqueous solvent are used as plating together, it can Inhibit above-mentioned unnecessary reaction.Also, further research is repeated based on the opinion, so as to complete the present invention.

That is, electroconductive particle of the invention has the metal envelope of the core particle containing aluminium (Al) and coating core particle, gold Belonging to envelope has the electric conductivity higher than core particle, and metal envelope is 80% or more to core particle surface covering rate.

About above-mentioned electroconductive particle, the average grain diameter of core particle is preferably 0.1 μm or more and 50 μm or less.

In addition, preferably metal envelope contains selected from by gold (Au), silver (Ag), copper (Cu), nickel in above-mentioned electroconductive particle (Ni), at least one kind of in the group that platinum (Pt), palladium (Pd), tin (Sn), zinc (Zn), cobalt (Co), chromium (Cr) and their alloy are constituted More than.

In addition, preferably the film thickness of metal envelope is 10nm or more in above-mentioned electroconductive particle.

In addition, the amount of the metal envelope of preferably coating core particle is 1 in electroconductive particle in above-mentioned electroconductive particle Quality % or more and 80 mass % or less.

In addition, the invention further relates to contain above-mentioned electroconductive particle as the conductive resin composition of conduction material and There is the coating material that film is formed by by the conductive resin composition on matrix.

The manufacturing method of electroconductive particle of the invention comprises the following steps: molten in the mixing containing organic solvent and aqueous solvent The process of the core particle containing Al is added in agent；Core particle is carried out in the in the mixed solvent addition etchant containing core particle The process of etching；And metal salt and reducing agent are further added in the mixed solvent, thus on the surface of etched core particle Form the process with the conductive metal envelope higher than core particle.

In the manufacturing method of above-mentioned electroconductive particle, preferable organic solvent contain alcohol series solvent, glycol ether series solvent and At least one or more in ketone series solvent.

In addition, the manufacturing method about above-mentioned electroconductive particle, in the work of the process and formation metal envelope that are etched In sequence, preferably the volume ratio of the organic solvent of in the mixed solvent is 10% or more and 90% or less.

In addition, the manufacturing method about above-mentioned electroconductive particle will mix molten preferably in the process for forming metal envelope The temperature of agent is adjusted to 0 DEG C or more and 60 DEG C or less.

Invention effect

Electroconductive particle, the conductive resin composition containing it and electric conductivity coating material of the invention, by utilizing gold Belong to envelope and be fully coated the core particle containing Al, to show the very useful effect of excellent electric conductivity.In addition, this hair The manufacturing method of bright electroconductive particle, which can be manufactured, is fully coated conduction made of the core particle containing Al using metal envelope Property particle.

Detailed description of the invention

Fig. 1 is the reflective electron picture (3000 times of multiplying power) of the sample of the electroconductive particle comprising embodiment 1.

Fig. 2 is the secondary electron image (2000 times of multiplying power) of the sample of the electroconductive particle comprising embodiment 1.

Fig. 3 is the secondary electron image (3000 times of multiplying power) of the sample of the electroconductive particle comprising embodiment 1.

Fig. 4 is the secondary electron image (2000 times of multiplying power) of the sample of the electroconductive particle comprising comparative example 1.

Fig. 5 is the secondary electron image (2000 times of multiplying power) of the sample comprising aluminum particulate.

Fig. 6 is the figure for indicating the image for the state deleted in the reflective electron picture by Fig. 1 there is no the region of particle.

Fig. 7 is the figure for indicating black white binarization treated image.

Specific embodiment

Hereinafter, electroconductive particle of the invention, the manufacturing method of electroconductive particle, the conduction containing it is described in more detail Property resin combination and electric conductivity coating material.

" electroconductive particle "

Electroconductive particle of the invention has the core particle containing Al and is coated the metal envelope of the core particle, metal envelope With the electric conductivity higher than core particle, metal envelope is 80% or more to core particle surface covering rate.Additionally, it is preferred that above-mentioned coating Rate is 85% or more.In this specification, so-called covering rate refers to the area being coated in the area of core particle using metal envelope Ratio (%), such as can according to utilize scanning electron microscope (SEM, Scanning Electron Microscope) institute The image analysis of the image of acquisition is found out based on following formula (1).

Covering rate (%)={ S1/ (S1+S2) } × 100... (1)

(in formula (1), S1 indicates that the area for the core particle being coated using metal envelope, S2 are indicated not by metal envelope quilt The area of the core particle covered).

It should be noted that in the present specification, surface covering rate is result measured by particle to 50 or more Average value.

About electroconductive particle as characterized above, since core particle contains Al, can have and be less than such as Ag particle The specific gravity of particle comprising other metals, therefore the reduction of the operability as caused by the sedimentation of above-mentioned particle can be prevented.In addition, logical Crossing makes core particle contain cheap Al, more inexpensively provides than the above-mentioned particle comprising other metals.In turn, due to core particle Surface 80% or more (preferably 85% or more) wider area by have higher than core particle electric conductivity metal envelope It is coated, therefore had not only had the advantages that cheap and specific gravity was lesser above-mentioned, but also there is electric conductivity sufficiently high.In addition, based on should be compared with High covering rate, it is less in the Al of the exposing on surface, therefore can inhibit the generation of corrosion, carry out, it as a result can fully maintain to lead Electrically.

It should be noted that describing the technology think of for obtaining the aluminium powder that silver-colored covering rate is 50% or more in patent document 4 Think, but the inventors of the present invention study technology disclosed Patent Document 4, as a result confirms that the manufacture of electroconductive particle is tired It is difficult, however, it is difficult to obtain the aluminium powder that silver-colored covering rate is 50% or more (referring to following comparative examples 2 and 3).It is believed that this situation Caused by unstability when being the plating processing as using the Al of aqueous solvent.

In addition, although electroconductive particle of the invention can be made by using the manufacturing method of following electroless plating methods It makes, but such electroconductive particle is characteristically different from through other plating, such as galvanoplastic or various dry type platings Electroconductive particle manufactured by method.Specifically, in galvanoplastic, due in the formation of metal envelope using electricity, therefore particle that This is easy cohesion and is difficult to form metal envelope in heterogeneity on each particle.In addition, usually being only capable of being formed in dry type plating The metal envelope of film thickness number nm or so can not form the metal envelope of the tens of nm of film thickness.In contrast, electroless plating method In, due to being difficult to cause the mutual cohesion of particle, metal envelope can be formed in heterogeneity on each particle, additionally it is possible to freely Adjust the film thickness of metal envelope.

As the shape of above-mentioned electroconductive particle, there is no particular restriction, can enumerate ball shape, elliptical shape, flat pattern The various shapes such as (sheet), gourd shape, polyhedron-shaped.Especially from going out because of the viewpoint of the small and easy plating of specific surface area Hair, preferably ball shape.It should be noted that in the present specification, so-called ball shape does not mean that spherical shape mathematically, but Referring to naked eyes can determine whether as the shape of spherical degree.

The average grain diameter of above-mentioned electroconductive particle is preferably 0.1 μm or more and 50 μm hereinafter, more preferably 1 μm or more and 40 μm or less.In the case where the average grain diameter of above-mentioned electroconductive particle is less than 0.1 μm, there are the operability of above-mentioned electroconductive particle Decline, for example, mixed with resin and whens manufacturing the situation etc. of conductive resin composition, situation that workability is remarkably decreased.Separately Outside, in the case where average grain diameter is more than 50 μm, there is also its operability declines, such as constitute coating on being coated on substrate In the case where object, the flatness on the surface of coating material is damaged sometimes.It should be noted that so-called average grain diameter in the present invention, is Refer to based on by size distribution measured by determination of particle size distribution well known to laser diffractometry etc., calculating its bulk averaged value and The volume average particle size found out.

In addition, the amount for being coated the metal envelope of core particle is preferably 1 in electroconductive particle in above-mentioned electroconductive particle Quality % or more and 80 mass % are hereinafter, more preferably 10 mass % or more and 60 mass % or less.In electroconductive particle, quilt Cover the amount of the metal envelope of core particle in electroconductive particle less than 1 mass % when, can not since metal envelope becomes too thin The electric conductivity of electroconductive particle is sufficiently improved, it is not preferable, and the amount of metal envelope is in above-mentioned electroconductive particle more than 80 matter When measuring %, the amount of metal caused by the metal envelope gets higher cost due to becoming excessive, thus not preferred.It should be noted that (metal envelope is shared in electroconductive particle by quality % of the metal envelope on the surface of coating core particle in electroconductive particle Amount) it can be measured based on the known method of metal quality, such as atomic absorption can be measured.

In addition, above-mentioned electroconductive particle preferably has at least 30 or more L from the viewpoint of design^*Value, more preferably With 40 or more L^*Value further preferably has 60 or more L^*Value.So-called L^*Value, refers to CIE1976L^*a^*b^*The colour space (CIELAB) CIE1976 brightness, numerical value is bigger, indicates that tone is brighter, L shown in JISZ8729^*Value is correspondingly.It needs Illustrate, colour examining uses secondary light source C specified in JISZ8720 with light source.

It should be noted that electroconductive particle of the invention can also contain inevitable impurity, as long as in addition, can play Effect of the invention out can also then contain any other ingredient.

Core particle is the particle to form the core of electroconductive particle of the invention, contains Al.Specifically, core particle can be only It is made of Al, can also be aluminium alloy.As aluminium alloy, can enumerate comprising as main metal Al and be selected from silicon (Si), magnesium (Mg), The alloy etc. of at least one or more in transition metal.Especially from the viewpoint of the easiness of the easiness, acquisition that industrially produce It sets out, preferably core particle is only made of Al.

There is no particular restriction for the shape of above-mentioned core particle, can enumerate ball shape, elliptical shape, flat pattern (sheet), calabash The various shapes such as reed shape, polyhedron-shaped.Especially from the viewpoint of because of the small and easy plating of specific surface area, preferably ball Shape.In addition, the core particle of ball shape also has due to easy to manufacture by inactive gas spray-on process or nitrogen spray method It is easy the advantages of obtaining.

In addition, the average grain diameter of above-mentioned core particle is preferably 0.1 μm or more and 50 μm or less.In average grain diameter less than 0.1 μ When m, manufacture is difficult, and as particle becomes easy cohesion, operability declines, therefore impracticable.In addition, super for average grain diameter For the case where crossing 50 μm, there is the possibility for the problems such as generating uneven dispersion, masking force decline when being engaged in resin, from this From the aspect of without preferred.

As such core particle, such as it can be used and pass through well known atomization, crush method, rotating disk method, electric rotating Pole method, cavitation corrosion method, whirl spraying smelting process etc. and obtain powder.In addition, it is possible to use made by Physical Processing through these methods And the powder obtained is deformed into flat particle.Especially, it is preferable to use passing through from the viewpoint of manufacturing cost, uniformity The powder that atomization obtains is as core particle.

It should be noted that core particle of the invention can also contain inevitable impurity, as long as in addition, can play this The effect of invention, then constituting the purity (%) of the Al or Al alloy of core particle, there is no particular restriction, from the viewpoint of electric conductivity, Preferably 92.5% or more.

Metal envelope is coated 80% or more (preferably 85% or more) on the surface of above-mentioned core particle, has higher than core particle Electric conductivity.It is preferred that the metal envelope contains selected from by Au, Ag, Cu, Ni, Pt, Pd, Sn, Zn, Co, Cr and their alloy structure At group at least one or more.From the viewpoint of easiness prepared by operability, sample, preferably metal envelope includes a kind Metal.Especially from the viewpoint of electric conductivity and cost, the metal envelope of Ag is preferably comprised.

In addition, the film thickness of above-mentioned metal envelope is preferably 10nm or more and 350nm or less.In addition, in the shape of core particle In the case where spherical, the film thickness of above-mentioned metal envelope be preferably 30nm or more and 100nm hereinafter, further preferably 50nm with Upper and 100nm hereinafter, in the case where the shape of core particle is sheet, the film thickness of above-mentioned metal envelope be preferably 10nm or more and 100nm or less.In the case where the film thickness of metal envelope is less than 10nm, electroconductive particle can not have electric conductivity sufficiently high, If the film thickness of metal envelope is more than 350nm, without preferred from the aspect of particle becomes easy cohesion.In metal envelope In the case that film thickness is 50nm or more, covering rate can further improve.

It should be noted that the film thickness of metal envelope can for example be found out in the following way: micro- using scanning electron The section of arbitrary 20 electroconductive particles of sem observation finds out its calculation to the thickness of 5 positions of each particle assay metal envelope Art average value, using this arithmetic mean of instantaneous value as average thickness.

It should be noted that metal envelope of the invention can also contain inevitable impurity.As long as in addition, can play Effect of the invention, then constituting the purity of the metal of metal envelope, there is no particular restriction, from electric conductivity and the sight of plastic processing Point sets out, and above-mentioned purity is preferably 92.5% or more.

As described above, electroconductive particle of the invention can both play cheap and the lesser core particle of specific gravity Above-mentioned advantage, and there is electric conductivity sufficiently high.In addition, can inhibit corruption since the part of the Al exposed on surface is less As a result the Emergence and Development of erosion can fully maintain electric conductivity.Therefore, electroconductive particle of the invention shows excellent electric conductivity Extremely favourable effect.

" conductive resin composition "

The invention further relates to contain conductive resin composition of the above-mentioned electroconductive particle as conduction material.Of the invention leads Conductive particles can solve above-mentioned technical problem, and the conductive resin composition for containing the electroconductive particle as conduction material can be inherited The effect of above-mentioned electroconductive particle.That is, conductive composition according to the present invention, can inhibit leading in conductive resin composition The sedimentation of conductive particles, therefore result can have high operability.In addition, conductive resin composition of the invention can have height Electric conductivity, in addition, can not only maintain its electric conductivity, but also can inexpensively provide.

Specifically, above-mentioned conductive resin composition is combination made of being scattered in above-mentioned electroconductive particle in resin Object can enumerate conductive paste, conductive coating paint, conductive adhesive, conductive ink, conductive membrane etc..It is such to lead Electrical resin combination can for example be manufactured and mediating above-mentioned electroconductive particle into resin.

Above-mentioned resin may be used at known resin used in this kind of purposes, such as can enumerate thermohardening type propylene Acid resin/melamine resin, thermohardening type acrylic resin/cellulose acetate-butyrate (CAB)/melamine resin, thermohardening type Polyester (alkyd) resin/melamine resin, thermohardening type polyester (alkyd)/CAB/ melamine resin, isocyanate curing type polyurethane Resin/normal temperature cured type acrylic resin, water dilution type acrylic compounds emulsion/melamine resin etc..

It should be noted that the content of the electroconductive particle in conductive resin composition is different because of purposes, therefore have no It is particularly limited to, is preferably for example set as 10 mass parts or more and 100 below the mass relative to 100 mass parts of resin.It is being less than When 10 mass parts, there are the situations that the electric conductivity of conductive resin composition becomes inadequate, and when more than 100 mass parts, have When because the amount of the electroconductive particle in conductive resin composition it is excessive, and make operational decline.In addition, above-mentioned electric conductivity combination Object contains the arbitrary ingredient other than resin and electroconductive particle.As arbitrary ingredient, such as can enumerate: frit, Metal alkoxide, viscosity modifier, surface conditioner.

" electric conductivity coating material "

The invention further relates to a kind of to have the coating that film is formed by by above-mentioned conductive resin composition on matrix Object.As described above, conductive resin composition of the invention is the substance that can inherit the effect of electroconductive particle of the invention, because This, electric conductivity of the invention can also be inherited by the coating material that the conductive resin composition is formed by film by having on matrix The effect of particle.

About above-mentioned electric conductivity coating material, specifically, conductive coating, electrode, wiring, circuit, electric conductivity can be enumerated Connected structure, electroconductive pressure-sensitive adhesive tape etc..The shape and thickness of film are also not particularly limited, and can be used required according to its purposes Thickness.

It can be inorganic matters, paper and the timber such as organic matters, ceramics, the glass such as metal, plastic cement etc., original about above-mentioned matrix Material is not particularly limited.

It is not particularly limited it should be noted that conductive composition of the invention is coated on the method on matrix, it can Using known coating method, any method can be used.

" manufacturing method of electroconductive particle "

The manufacturing method of electroconductive particle of the invention comprises the following steps: molten in the mixing containing organic solvent and aqueous solvent The process of the core particle containing Al is added in agent；Core particle is carried out in the in the mixed solvent addition etchant containing core particle The process of etching；And in the mixed solvent further add metal salt and reducing agent and in the surface of etched core particle, shape At the process of the metal envelope with the electric conductivity higher than core particle.Hereinafter, being described in detail to each process of the invention.

This process is the process in core particle of the in the mixed solvent addition containing Al comprising organic solvent and aqueous solvent.

By this process, the core particle of the core of electroconductive particle can be become, is being become in advance for carrying out plating processing Reaction solution in the mixed solvent dispersion.

In addition, the core particle sometimes with Al is attached with the dirts such as grease, in this case, in the past must using only by The reaction solution that aqueous solvent is constituted carries out the pre-treatments such as degreasing, the cleaning of core particle before being handled.But in contrast, originally In invention, due to adding core particle, oil accompanying by core particle in the in the mixed solvent comprising organic solvent and aqueous solvent The dirts such as rouge can be removed by organic solvent from the surface of core particle.Therefore, according to the present invention, can omit previous necessary Pre-treatment, therefore manufacturing cost can be reduced.

In this process, it is preferably stirred solvent.Above-mentioned core particle can be made to spread more evenly across to mixed solvent as a result, In, therefore can be efficient and steadily carry out managing everywhere in subsequent each process.Stirring means can be used well known any Method, such as blenders or the ultrasonic waves such as jet agitation machine, High-shear mixers can be used.In addition, by combining these hands Section, can carry out dispersion more evenly in a short time.

It should be noted that being constituted, such as composition, shape, manufacturing method about the preferred of core particle, led with above-mentioned The core particle of conductive particles is identical, therefore repeats no more.

Above-mentioned mixed solvent includes organic solvent and aqueous solvent, as long as not interfering the etching reaction and plating in subsequent each process Reaction is applied, then can also contain other compositions, such as ionic liquid.Wherein, from the viewpoint of manufacturing cost, preferably only It is made of organic solvent and aqueous solvent.

Above-mentioned organic solvent is not particularly limited, preferably the organic solvent high with the compatibility of water, in particular, more preferably Contain at least one or more in alcohol series solvent, glycol ether series solvent and ketone series solvent.In the past, addition included Al in aqueous solvent Particle as core particle in the case where, due to being reacted with Al with the unnecessary of water vigorous reaction, exist and be difficult to control The problem of reaction in subsequent handling processed.In contrast, in this process, be added to comprising organic solvent due to core particle and The mixed solvent of aqueous solvent, therefore can inhibit such as previous above-mentioned unnecessary reaction.In addition, high using the compatibility with water Organic solvent as organic solvent in the case where, these organic solvents are due to having aqueous solvent and being higher than with polarity The Combination (compatibility) of other organic solvents, therefore the mixed solvent containing these organic solvents and aqueous solvent is difficult to separate, It is easy to keep admixture.Therefore, the various processing in subsequent each process can steadily be carried out.

As preferred alcohol series solvent, methanol, ethyl alcohol, isopropanol, normal propyl alcohol, the tert-butyl alcohol, n-butanol, isobutyl can be enumerated Alcohol.As preferred glycol ether series solvent, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropyl two can be enumerated Alcohol monomethyl ether.As preferred ketone series solvent, acetone, methyl ethyl ketone can be enumerated.It should be noted that aqueous solvent is not special Any water in industrial water, purified water, ion exchange water, ultrapure water etc. can be used in limitation, from can inhibit metal ion with Ion in aqueous solvent is formed from the perspective of sediment, preferred ion exchanged water.

It should be noted that the volume ratio of the organic solvent of in the mixed solvent is not particularly limited, preferably in this process With in aftermentioned etching work procedure and formation metal, by membrane process, volume ratio can be easily adjusted to the side in aftermentioned range Formula adjusts its volume ratio in this process.

This process is the process adding etchant to the in the mixed solvent containing core particle and being etched to core particle.

Core particle contains Al as described above, therefore there are oxidation films on its surface.The shape in the case where not removing the oxidation film When at metal envelope, oxidation film shows insulating properties, thus can not obtain the electroconductive particle with high conductivity.In contrast , the present invention in, before forming metal envelope, core particle is etched in this process first.It can remove and deposit as a result, It is the oxidation film on the surface of core particle.

In addition, as described above, the previous method that plating processing is carried out in aqueous solvent there are the following problems: due to Al with Etchant excessively tempestuously reacts, in addition, therefore, it is difficult to needed for controlling with the unnecessary reaction that Al is tempestuously reacted with water Reaction.In contrast, in the present invention, being etched in for Al is carried out comprising the in the mixed solvent of organic solvent and aqueous solvent. It can control unnecessary reaction as described above as a result, therefore can fully remove the oxidation film for being present in the surface of core particle, And it can inhibit core particle exceedingly to be etched.

As long as above-mentioned etchant can dissolve or be dispersed in the mixed solvent, used in the etching that previous Al may be used Acid, alkali etc..As acid, any substance in organic acid, inorganic acid and their salt can be used.It, can as preferred organic acid Enumerate citric acid, succinic acid, malic acid, oxalic acid, ascorbic acid etc.；As preferred inorganic acid, hydrochloric acid, sulfuric acid, boron can be enumerated Acid, phosphoric acid etc.；As these organic acids and the respective salt of inorganic acid, sodium salt, sylvite etc. can be enumerated.In addition, as preferred Alkali can enumerate sodium hydroxide, potassium hydroxide, ammonium hydroxide.In particular, will mixed in the aftermentioned process for forming metal envelope In the case that the pH value of solvent is adjusted to alkalinity, it is preferable to use alkali from the viewpoint of becoming easy the adjustment.

In addition, complexing agent can also further be added in the mixed solvent.Complexing agent is to inhibit the Al being etched again It is precipitated and is formed with Al the substance of complex compound.Specifically, the hydroxyls carboxylics such as carboxylic acids, citric acid and the tartaric acid such as succinic acid can be used Acid, glycine, ethylenediamine tetra-acetic acid (EDTA), amino acid etc. and their salt, such as alkali metal salt, ammonium salt.This process In, by using such complexing agent, it can inhibit being precipitated again for Al, therefore stable etching can be carried out.

Mixed solvent in this process, the volume ratio for adding the in the mixed solvent organic solvent after the additives such as etchant Example preferably 10% or more and 90% is hereinafter, more preferably 30% or more and 70% or less.By the way that above-mentioned volume ratio is set as 10% or more, the adjoint unnecessary etching of the overreaction of Al and etchant can be adequately suppressed.In addition, by will be above-mentioned Volume ratio is set as 90% hereinafter, undercut caused by the extra-inhibitory of etching reaction can be avoided fully.In addition, passing through Above-mentioned volume ratio is set as 30% or more and 70% hereinafter, said effect can be played effectively further, it in turn, will be aftermentioned Formation metal is adjusted to specific volume ratio by the above-mentioned volume ratio in membrane process and becomes easy.

In addition, the processing time of this process is preferably 10 seconds or more and 120 seconds or less.When less than 10 seconds, because etching becomes It is insufficient, cause the removal of the oxidation film on core particle surface to become inadequate, as a result exists and become difficult to obtain with highly conductive The tendency of the electroconductive particle of property.More than 120 seconds, because of over etching, etchant reacts with core particle, becomes It must be easy to generate the reaction products such as hydroxide.It hinders to form aftermentioned metal envelope moreover, the reaction product becomes Process will be because, therefore result becomes difficult to obtain the electroconductive particle with high conductivity.

In addition, being preferably stirred to the mixed solvent added with core particle and etchant in this process.Make core as a result, Particle and etchant are uniformly dispersed in the mixed solvent, therefore can be effectively etched to core particle.

This process is further to add metal salt and reducing agent in the mixed solvent, thus in the table of etched core particle Face forms the process with the metal envelope of the electric conductivity higher than core particle.As carry out the process of plating processing.

For the effect of this process, illustrate while being compared with well-known technique.Firstly, as described above, exist in the past There are the following problems for the method for progress plating processing in aqueous solvent: since Al is excessively tempestuously reacted with etchant, in addition, with The unnecessary reaction that Al is tempestuously reacted with water, therefore, it is difficult to control required reaction, be as a result unable to fully to core particle It is coated.In contrast, according to this process, the formation of metal envelope is in the mixing comprising organic solvent and aqueous solvent It is carried out in solvent.It can inhibit above-mentioned unnecessary reaction as a result, therefore can manufacture and be fully coated using metal envelope Electroconductive particle with high conductivity.

In addition, it is previous, when being moved to the core particle for removing oxide film dissolving by etching in following plating treatment fluids, because Core particle takes out from etching solution and is exposed in atmosphere, thus the case where forming oxidation film again there are the surface of core particle. In contrast, according to this process, due to metal needed for further adding plating processing to the mixed solvent containing etchant Salt and reducing agent, core particle are not exposed in atmosphere.It is therefore possible to prevent oxidation film is re-formed to the core particle after etching, and And metal envelope can be formed.Can inhibit the decline of the electric conductivity because caused by there are oxidation film as a result, thus can yield rate it is good It manufactures well and has been sufficiently carried out the coating electroconductive particle with high conductivity using metal envelope.

In addition, it is previous, if the etching of core particle and the formation of metal envelope are carried out in a treatment fluid simultaneously, deposit In following situation: on the surface of core particle, etched a part of region starts that the metal for constituting metal envelope is precipitated.This feelings Under condition, it will form local cell in the region that metal is precipitated, with the formation of the localizing electrode, promote the dissolution of local Al anti- It answers, thus the control for dissolving reaction is complicated, difficultization, as a result in the presence of the feelings for the metal film envelope that can not form homogeneous Condition.In contrast, according to the present invention, the process to form metal envelope is carried out after the process of etching.It can eliminate as a result, Above-described problem, thus can yield rate manufacture utilize the metal envelope fully coating conduction with high conductivity well Property particle.

Above-mentioned metal salt used in this process can preferably be stablized in the in the mixed solvent comprising organic solvent and aqueous solvent The salt of ground dissolution, can be used nitrate, sulfate, nitrite, oxalates, carbonate, chloride, acetate, lactate, ammonia Base sulfonate, fluoride, iodide, cyanide etc..

Metal contained in metal salt is converted into the metal for constituting metal envelope by this process.The metal has than core The high electric conductivity of particle, particularly preferably from the group being made of Au, Ag, Cu, Ni, Pt, Pd, Sn, Zn, Co, Cr and their alloy Middle selection.These metals and alloy have the electric conductivity more sufficiently high than core particle, thus can manufacture using with high conductivity as mesh Target electroconductive particle.

Wherein, using Au, Ag, Pt, effect of the invention becomes more significant.Itself the reason is as follows that.That is, making In electroless plating method with previous aqueous solvent, standard electrode potential and Au, Ag, Pt's of the Al due to constituting core particle is each The difference of standard electrode potential is especially big, therefore exists and be particularly difficult to equably constitute the metal envelope comprising metal any in these Tendency.In contrast, in this process, in the case where in the mixed solvent carries out electroless plating method, even with this A little metals can also manufacture the electroconductive particle being fully coated using metal envelope.Wherein, go out from the viewpoint of electric conductivity and cost Hair is, it is preferable to use Ag.

Reducing agent is the substance that the metal generated by metal salt is precipitated in the surface reduction of core particle in the mixed solvent. Specifically, the carbohydrates such as glucose, sucrose, the polysaccharides such as cellulose, starch, glycogen can be used；Ethylene glycol, propylene glycol, glycerol Equal polyalcohols；Hypophosphorous acid, formaldehyde, boron hydride, dimethylamine borane, trimethylamine borane, hydrazine tartaric acid etc..It should be noted that Hydrazine tartrate preferred as alkali salt.

In addition, complexing agent can also further be added in the mixed solvent.Complexing agent is for inhibiting Al generated again It is precipitated and is formed with Al the substance of complex compound.Specifically, the hydroxyls carboxylics such as carboxylic acids, citric acid and the tartaric acid such as succinic acid can be used Acid, glycine, ethylenediamine tetra-acetic acid (EDTA), amino acid etc. and their salt, such as alkali metal salt, ammonium salt.This process In, by using such complexing agent, it can inhibit being precipitated again for Al, therefore metal envelope can steadily be made to grow up.

Mixed solvent in this process adds the organic molten of the in the mixed solvent after the additives such as metal salt and reducing agent The volume ratio of agent is preferably 10% or more and 90% hereinafter, more preferably 30% or more and 70% or less.In above-mentioned volume ratio In the case that example is less than 10%, excessive plating is inhibited to react with being unable to fully, the possibility for having Al unnecessarily to dissolve.In addition, In the case that above-mentioned volume ratio is more than 90%, there is the possibility of the plating reaction needed for inhibiting.In addition, by by above-mentioned volume ratio Example is set as 30% or more and 70% hereinafter, the degree of plating reaction can be adjusted more appropriately.

In addition, in this process, it, particularly preferably will be added with additive in the case where forming the metal envelope comprising Ag The pH value of mixed solvent is adjusted to alkaline, and more preferably 8 or more and 12 or less.Its reason is: compared with acid condition, alkalinity Under the conditions of be easier to control Ag plating reaction.It should be noted that the pH value of mixed solvent can pass through above-mentioned reducing agent, network The additive amount of mixture etc. is adjusted, and can also be held ands adding sodium hydroxide, potassium hydroxide or ammonium hydroxide etc. in the mixed solvent It changes places and is adjusted.

In addition, the temperature of mixed solvent is preferably adjusted to 0 DEG C or more and 60 DEG C hereinafter, more preferably 5 in this process DEG C or more and 50 DEG C hereinafter, further preferably 10 DEG C or more and 35 DEG C or less.The case where the temperature of mixed solvent is less than 0 DEG C Under, the formation speed of metal envelope becomes too slow and inefficiency.In addition, in the case that the temperature of mixed solvent is more than 60 DEG C, shape Become too fast at speed, thus becomes difficult to form uniform metal envelope.

In addition, the processing time of this process is preferably 15 minutes or more and 120 minutes hereinafter, more preferably 30 minutes or more And 90 minutes or less.In the case where handling the time less than 15 minutes, there are platings to react insufficient, and core particle is coating sometimes Amount is less than 80%.In addition, the unnecessary reaction of in the mixed solvent carries out, and mixes sometimes if the processing time is more than 120 minutes Gelation occurs for solvent.

In addition, being preferably stirred to mixed solvent in this process.It can make core particle and other compositions equably as a result, It is dispersed in the mixed solvent, therefore can inhibit the mutual cohesion of core particle, and the reaction of target can be made equal in the mixed solvent Occur evenly, therefore metal envelope can be effectively formed on the surface of core particle.

As long as the manufacturing method of electroconductive particle of the invention carries out above-mentioned each process, other processes can also be contained.Make For other processes, such as can enumerate: before adding core particle to mixed solvent, process that core particle is cleaned；It will be manufactured The process etc. taken out from the mixed solvent of electroconductive particle.

As set forth in more detail above, manufacturing method according to the invention can inhibit unnecessary reaction on one side, pass through etching on one side The oxidation film on the surface of the core particle containing aluminium is removed, and then can continue to inhibit unnecessary reaction on one side, on one side in above-mentioned core Form metal envelope to the surface-stable of particle.Therefore, as a result, the control of the reaction in the formation of metal envelope becomes to hold Easily, the electroconductive particle that core particle is fully coated using metal envelope can thus be manufactured.

Specifically, manufacturing method according to the invention, can manufacture metal envelope is 80% to core particle surface covering rate Above electroconductive particle.Show that the electroconductive particle of high covering rate there can be the metal because constituting metal envelope as a result, Bring high conductivity.In addition, preparation contains manufactured electric conductivity by using such as specific gravity small core particle containing aluminium When conductive resin composition of the particle as conduction material, with other electroconductive particle phases such as the electroconductive particle that is only made of silver Than can inhibit its sedimentation, therefore result its operability becomes excellent.In turn, by using containing the aluminium that can inexpensively obtain Core particle can reduce the manufacturing cost of electroconductive particle.

In addition, the manufacturing method of the present invention uses electroless plating method, manufactured electroconductive particle is in the following areas not It is same as through electroconductive particle manufactured by other manufacturing methods such as electrolytic plating method, dry type plating.That is, in galvanoplastic, Using electricity when due to forming metal envelope, particle is easy cohesion each other, to be difficult to be formed in heterogeneity on each particle Metal envelope.In addition, usually can only form the metal envelope of film thickness number nm or so in dry type plating, film thickness can not be formed The metal envelope of tens of nm.In contrast, in electroless plating method, due to being difficult to cause the mutual cohesion of particle, Metal envelope can be formed in heterogeneity on each particle, in addition, the film thickness of metal envelope can be adjusted freely.

As set forth in more detail above, the manufacturing method of electroconductive particle of the invention can be manufactured contains comprising above-mentioned electroconductive particle There is the core particle of Al and be coated the metal envelope of the core particle, and metal envelope has the electric conductivity higher than core particle, metal quilt The electroconductive particle that film is 80% or more to core particle surface covering rate.

In addition, plating used in the present invention is the electroless plating method as one of wet type plating.Therefore, with it is dry Formula plating is compared, and is not necessarily to large-scale device, and can disposably manufacture a large amount of electroconductive particle.

Embodiment

Hereinafter, enumerating embodiment is described in more detail the present invention, but the present invention is not limited to these.

" research 1 "

1. the preparation of material

Prepare material below.

As core particle use from ball shape to granular form Al powder (5 μm of average grain diameter, Japan's aluminium Co. Ltd. system It makes).It uses as mixed solvent by 50 liters of isopropanol (IPA) and 200 liters of solvents mixed of ion exchange water.As etching Agent by sodium hydroxide 566g using mixing to IPA and be adjusted to 10 liters of etching solution.It should be noted that the etching solution It is functioned as pH adjuster.As metal salt and complexing agent, using to adding silver nitrate 1415g in 6.4 liters of ammonium hydroxide, and 10 liters of silver nitrate aqueous solution is adjusted to using ion exchange water.That is, silver nitrate is as metal contained in silver nitrate aqueous solution Salt functions, and ammonia is functioned as complexing agent.Glucose 4.3kg is mixed into IPA simultaneously in addition, being used as reducing agent It is adjusted to 10 liters of reducing agent solution.

2. the manufacture of electroconductive particle

Firstly, adding 2kg Al powder in the mixed solvent, mixed solvent is stirred using clamp-type jet agitation machine It mixes.Core particle is set to be dispersed in the mixed solvent (" addition process ") as a result,.Then, etching solution is added in the in the mixed solvent It 1.75 liters, continuously stirs 90 seconds, thus carries out the etching (" etching work procedure ") of core particle.Next, adding in the in the mixed solvent Add 8.25 liters of remaining etching solution, 10 liters of silver nitrate aqueous solution and 10 liters of reducing agent solution.Then, by the mixed solvent Liquid temperature is adjusted to 27 DEG C and stirs 30 minutes, to carry out plating processing (" process for forming metal envelope ").

After above-mentioned processing, separation is filtered to slurry caused by the mixed solvent, utilizes ion exchange water and methanol The slurry being separated by filtration is cleaned.Then, make the slurry of cleaning dry under 130 DEG C of vacuum environment.Conduct is obtained as a result, The aluminum particulate for the coating silver that the Al particle of core particle is coated by the envelope comprising Ag, as electroconductive particle.

1. the preparation of material

As core particle use from ball shape to granular form Al powder (6 μm of average grain diameter, Japan's aluminium Co. Ltd. system It makes).It uses as mixed solvent by 3.4 liters of 1 liter of IPA, 1 liter of n-butanol and ion exchange water solvents mixed.As erosion Agent is carved using mixing sodium hydroxide 189g to IPA and be adjusted to 1.4 liters of etching solution.It should be noted that the etching is molten Liquid is also functioned as pH adjuster.It is used as metal salt and complexing agent and adds silver nitrate in 2.1 liters of ammonium hydroxide 472.4g is simultaneously adjusted to 2.5 liters of silver nitrate aqueous solution.That is, silver nitrate contained in silver nitrate aqueous solution is played as metal salt Function, ammonia are functioned as complexing agent.Glucose 710g is mixed into n-butanol and adjusted in addition, being used as reducing agent For 1.4 liters of reducing agent solution.

2. the manufacture of electroconductive particle

Firstly, adding Al powder 700g in the mixed solvent, mixed solvent is stirred using clamp-type jet agitation machine It mixes, while carrying out the dispersion using ultrasonic wave.It should be noted that using the dispersion of ultrasonic wave using supersonic wave cleaning machine come real It applies.Core particle is set to be dispersed in the mixed solvent (" addition process ") as a result,.Then, above-mentioned etching is added in the in the mixed solvent Solution 15ml is simultaneously continuously stirred 30 seconds, thus carries out the etching (" etching work procedure ") of core particle.Then, add in the in the mixed solvent Add 2.5 liters of silver nitrate aqueous solution and 1.4 liters of reducing agent solution.Then, the liquid temperature of the mixed solvent is adjusted to 30 DEG C and stirred 60 minutes and carry out plating processing (process of metal envelope " formed ").

After above-mentioned processing, separation is filtered to slurry caused by the mixed solvent, utilizes ion exchange water and methanol Clean be separated by filtration slurry.Then, make the slurry of cleaning dry under 130 DEG C of vacuum environment.It obtains as a result, and is used as core The aluminum particulate for the coating silver that the Al particle of particle is coated by the envelope comprising Ag, as electroconductive particle.

1. the preparation of material

Prepare material below.

As core particle use from ball shape to granular shape of particle Al powder (33 μm of average grain diameter, Japan's aluminium strain Formula commercial firm manufacture).It is used as mixed solvent and rises IPA80 and 170 liters of solvents mixed of ion exchange water.As etching Agent by sodium hydroxide 553g using mixing into propylene glycol monopropyl ether and be adjusted to 10 liters of etching solution.It should be noted that The etching solution is also functioned as pH adjuster.Metal salt and complexing agent use are to adding silver nitrate in 6.2 liters of ammonium hydroxide 1381g is simultaneously adjusted to 10 liters of silver nitrate aqueous solution using ion exchange water.That is, silver nitrate contained in silver nitrate aqueous solution is made It is functioned for metal salt, ammonia is functioned as complexing agent.In addition, as reducing agent use by glucose 8.3kg mix to In propylene glycol monopropyl ether and it is adjusted to 10 liters of reducing agent solution.

2. the manufacture of electroconductive particle

Firstly, adding Al powder 3.3kg in the mixed solvent, mixed solvent is stirred using height shearing mixing machine. Core particle is set to be dispersed in the mixed solvent (" addition process ") as a result,.Then, 1 liter of etching solution is added in the in the mixed solvent And continuously stir 120 seconds, thus carry out the etching (" etching work procedure ") of core particle.Then, which is added remaining 9 liters of etching solution, 10 liters of silver nitrate aqueous solution and 10 liters of reducing agent solution.Then, the liquid temperature of the mixed solvent is adjusted to 43 DEG C and stir 45 minutes and carry out plating processing (process of metal envelope " formed ").

1. the preparation of material

Prepare material below.

As core particle use from ball shape to granular form Al powder (2.3 μm of average grain diameter, aluminium Co., Ltd., Japan Manufacture).It uses as mixed solvent by 7 liters of ethyl alcohol and 2.5 liters of solvents mixed of ion exchange water.It is used as etchant Sodium hydroxide 320g is mixed into IPA and is adjusted to 2.3 liters of etching solution.It should be noted that the etching solution is also made It is functioned for pH adjuster.Metal salt and complexing agent use are handed over to 2.0 liters of addition silver nitrate 800g of ammonium hydroxide and using ion Change the silver nitrate aqueous solution that water is adjusted to 2.3 liters.That is, silver nitrate contained in silver nitrate aqueous solution plays function as metal salt Can, ammonia is functioned as complexing agent.Glucose 1.2kg is mixed into ethyl alcohol and is adjusted in addition, being used as reducing agent 2.3 liters of reducing agent solution.

2. the manufacture of electroconductive particle

Firstly, adding Al powder 500g in the mixed solvent, mixed solvent is stirred using clamp-type jet agitation machine It mixes.Core particle is set to be dispersed in the mixed solvent (" addition process ") as a result,.Then, etching solution is added in the in the mixed solvent 180ml is simultaneously continuously stirred 90 seconds, thus carries out the etching (" etching work procedure ") of core particle.Then, it is added in the in the mixed solvent 2.1 liters of remaining etching solution, 2.3 liters of silver nitrate aqueous solution and 2.3 liters of reducing agent solution.Then, by the liquid of the mixed solvent Temperature is adjusted to 3 DEG C and stirs 30 minutes and carry out plating processing (" process for forming metal envelope ").

About material, mixed solvent is replaced to be set as same as Example 1 in addition to this using 250 liters of IPA.In addition, About the manufacture of electroconductive particle, the aluminum particulate for being coated silver is manufactured by method same as Example 1.

About material, mixed solvent is replaced to be set as and 2 phase of embodiment in addition to this using 5.4 liters of ion exchange waters Together.In addition, the manufacture about electroconductive particle, carries out method same as Example 2.

About material, mixed solvent is replaced to be set as and 3 phase of embodiment in addition to this using 250 liters of ion exchange waters Together.In addition, the manufacture about electroconductive particle, carries out method same as Example 3.

Find out the amount of coating (quality %) of the metal envelope on the electroconductive particle of each embodiment and each comparative example.

Specifically, firstly, preparing each sample made of being dissolved to each electroconductive particle in acid solution.Then, for Each sample is led using atomic absorption spectrophotometer (product name: " A-2000 ", the manufacture of Co., Ltd. Hitachi's high-tech) measurement Metal component contained in conductive particles.Moreover, calculating the mass ratio of Al/Ag according to the measurement result, it is based on the mass ratio, by Following formula (2) calculates the average amount of coating (quality %) of each electroconductive particle.The results are shown in tables 1.On it should be noted that It states each sample and uses following sample: after taking electroconductive particle in right amount, using the nitration mixture comprising nitric acid and hydrofluoric acid in room temperature Under with 30 minutes or so time make the electroconductive particle dissolve, and be diluted to suitable for measurement concentration made of sample.In addition, Measurement wavelength is 328.1nm, and gas condition is set as air acetylene.

Amount of coating (quality %)={ W1/ (W1+W2) } × 100... (2)

(in formula (2), W1 indicates to constitute the quality of the metal (Ag) of metal envelope, and W2 indicates to constitute the metal of core particle (Al) quality).

[table 1]

Find out the covering rate (%) of metal envelope in the electroconductive particle in each embodiment and each comparative example.

Specifically, firstly, preparing that each electroconductive particle is made to be dispersed to each sample on carbon ribbon.Then, using sweep type Electron microscope (product name: " JSM-5510 ", it is anufactured by Japan Electron Optics Laboratory(JEOL)) in acceleration voltage 5kV, measurement multiplying power 3000 The reflective electron picture of each sample is shot under conditions of times.By the reflective electron picture of the sample of the electroconductive particle comprising embodiment 1 (3000 times of multiplying power) is shown in Fig. 1.In Fig. 1, it is seen that the region of particle shape corresponds to electroconductive particle, between the electroconductive particle The region of gap visible black color corresponds to carbon ribbon.

In addition, as a reference, by the secondary electron image (2000 times of multiplying power) of the sample of the electroconductive particle comprising embodiment 1 It is shown in Fig. 2, the secondary electron image (3000 times of multiplying power) of the sample of the electroconductive particle comprising embodiment 1 is shown in Fig. 3, will include The secondary electron image (2000 times of multiplying power) of the sample of the electroconductive particle of comparative example 1 is shown in Fig. 4, by the sample comprising aluminum particulate Secondary electron image (2000 times of multiplying power) is shown in Fig. 5.It can be observed by Fig. 2 and Fig. 3: the surface phase of the electroconductive particle of embodiment 1 To smooth, which is coated in heterogeneity by metal envelope.On the other hand, can be observed by Fig. 4: the electroconductive particle of comparative example 1 Surface unevenly disperse that there are metal envelopes.In Fig. 4, the substance pair of its concave-convex surface is attached on electroconductive particle and made It should be in metal envelope.

Fig. 1 is returned to, (product name: " Photoshop (registered trademark) ", AdobeSystems are public using image processing software Department) processing that following (1)~(3) are carried out to captured reflective electron picture, metal envelope is thus calculated to electroconductive particle Covering rate (%).It should be noted that " covering rate (%) " in table 2 indicates the average coating of 50 or more electroconductive particles Rate.

(1) part (region of carbon ribbon occur) that particle is not present in reflective electron picture (Fig. 1) is deleted.Fig. 6 is indicated will The image for the state deleted in the reflective electron picture of Fig. 1 there is no the region of particle is visible black between electroconductive particle in Fig. 6 The region of white alternately trellis is equivalent to deleted region.

(2) black white binarization processing is carried out to the remaining area of Fig. 6 (black and white replaces the region other than trellis).Fig. 7 is black The region of image after white binary conversion treatment, black and white alternating trellis is equivalent to the region being deleted in above-mentioned (1) and black and white two-value The region with the attribute of white (level=1) is judged as in change processing, the region other than black and white alternating trellis is equivalent to black and white The region with the attribute of black (level=0) is judged as in binary conversion treatment.In the black white binarization processing of Fig. 6, it is determined It is equivalent to the region that Al exposes in electroconductive particle for the region with black attribute, is judged as the region for the attribute for having white It is equivalent to the region being coated in electroconductive particle by Ag.

(3) by replacing the black and white of image pixel number (A) i.e. Fig. 7 of the attribute with black (level=0) in Fig. 7 The black and white of image pixel number (B) i.e. Fig. 6 of the image pixel number and general image in Fig. 6 in the region other than trellis replaces lattice The image pixel number in the region other than shape substitutes into the formula of { (B-A)/B } × 100, calculates covering rate (%).

It should be noted that using the image of the particle comprising 50 or more about above-mentioned reflective electron picture.One when observation In the case that a image does not include 50 or more particles, change visual field when observation, prepares multiple images, merge them makes again With.

About the film thickness of metal envelope, scanning electron microscope (product name: " JSM-5510 ", Japan Electronics strain is utilized The manufacture of formula commercial firm) arbitrary 20 electroconductive particles of observation section, to the thickness of 5 positions of each particle assay metal envelope Degree, thus finds out its arithmetic mean of instantaneous value, using the arithmetic mean of instantaneous value as average thickness.

Find out the average grain diameter of the electroconductive particle of each embodiment and each comparative example.

Specifically, firstly, adding the powder (grain comprising each electroconductive particle in the sample bath that joined methanol 50ml The aggregate of son) 0.4g and make sample, 1 minute ultrasonic wave dispersion (15W) is carried out to the sample.Then, using laser diffraction/ Scattering formula particle size distribution analyzer (product name: " LA-300 ", manufactured by the production of hole field), which bathes the sample after rigid dispersion, to carry out The measurement of particle diameter distribution, measurement accumulate the partial size of the D50 of average size distribution, thus calculate average grain diameter.

It about coating metal rate, can clearly be learnt by table 2: be made using the mixed solvent comprising organic solvent and aqueous solvent The coating metal rate that the electroconductive particle for each embodiment made is 80% or more.In contrast, it is manufactured using organic solvent Comparative example 1 electroconductive particle be 50% lower coating metal rate below.

In addition, being conceived to embodiment 2 and embodiment 3, although the amount of coating (quality %) of its metal envelope is less than comparative example 1 Value, but its covering rate (%) display 80% or more.Thus speculate: by using mixed solvent, reacting appropriate in each process It is controlled, it thus can be in the metal envelope of the thickness of the whole surface of core particle formation more evenly.

In addition, can clearly learn that the average grain diameter of the electroconductive particle of comparative example 1 is shown by table 1 about average grain diameter The value more than multiple of the average size of the electroconductive particle of embodiment 1, this value are equivalent to the partial size of used Al powder Multiple more than value.On the other hand, about the amount of coating (quality %) of metal envelope, embodiment 1 shows biggish value.It is logical It often is difficult to think the amount of coating (quality %) with degree shown in table 1, the average grain diameter of electroconductive particle can reach as raw material Al powder partial size multiple more than.Therefore the electroconductive particle for speculating comparative example 1 is particle made of particle aggregates with one another.

It should be noted that in their manufacturing process, aqueous solvent and Al powder are acute about comparative example 2 and comparative example 3 Strong reaction, thus Al powder dissolves and gelation, thus cannot manufacture electroconductive particle.Thus can speculate: difficult using aqueous solvent To form metal envelope on the surface of Al powder, if above-mentioned electroconductive particle can be manufactured, manufacturing condition is also greatly limited System, manufactured electroconductive particle cannot keep constant quality.

" research 2 "

Film is formed using manufactured electroconductive particle in Examples 1 to 4 and comparative example 1.Each film is with electric conductivity The volume ratio of particle makes as 60% mode.

Specifically, about embodiment 1,2 and comparative example 1, by the aluminium powder 3g of coating silver and resin solution (trade name: " nippe acrylic auto clear super ", the manufacture of Nippon Paint society) 3g mixing, it will be obtained using applicator Mixture be coated in PET film in such a way that the coating thickness after drying becomes 30 μm, dry 30 minutes at 100 DEG C, Film is consequently formed.

In addition, about embodiment 3, mixed resin solution (same as described above) 3g in the aluminium powder 2.73g for being coated silver makes Obtained mixture is coated in PET film in such a way that the coating thickness after drying becomes 100 μm with applicator, 100 It is 30 minutes dry at DEG C, film is consequently formed.

In addition, about embodiment 4, mixed resin solution (same as described above) 3g in the aluminium powder 3.7g for being coated silver makes Mixture obtained is coated in PET film in such a way that the coating thickness after drying becomes 30 μm with applicator, 100 It is 30 minutes dry at DEG C, film is consequently formed.

It should be noted that the volume ratio of the electroconductive particle in film can be found out according to following calculating formulas.

Volume ratio (%)={ [(quality (g) of electroconductive particle/electroconductive particle specific gravity (g/cm³)]/[(resin The quality (g) of solution × resin solution solvent rate (%)/resin solution specific gravity (g/cm³))+(quality of electroconductive particle (g) × electroconductive particle specific gravity (g/cm³)] × 100 (wherein, the solvent rate (%) of resin solution is 32%).

In addition, the thickness of film is by utilizing digital display nominal outer diameter micrometer (trade name: " IP65 COOLANT PROOF Micrometer ", Mitutoyo Co., Ltd. manufacture) be measured and really with.

For each film, four probe-type sheet resistance analyzers (trade name: " Loresta GP ", Mitsubishi is used The manufacture of Analytech Co., Ltd.) arbitrary 5 points of measurement, using its average value as resistivity value (Ω cm).Specifically, The coordinate of the size of conductive coating, average coating thickness, measuring point is input to the measurement of four probe-type sheet resistances with data It in device, is calculated automatically, the resistivity value by thus obtained value as conductive coating.Show the result in table 2.It needs Bright, resistivity value is smaller, indicates that electric conductivity is more excellent.

[table 2]

<L^*Value >

For the Y value that each film, the method as documented by the condition a according to JIS-Z8722 measure, JIS-Z8729 is obtained The L as brightness of defined^*Value.Specifically, using polygonal spectral photometric colour measuring meter (trade name: " X-RiteMA-68II ", X- The manufacture of Rite company), it is measured by 45 degree of measurement angle.It the results are shown in table 2.It should be noted that the number of L value Value is higher, indicates that whiteness is higher.

About resistivity, comparative example 1 due to be formed by using metal envelope be coated it is insufficient, measurement when can not flow Fixed electric current is crossed, and can not be measured.In contrast, Examples 1 to 4 shows substantially low resistivity.By the situation Confirmation: the film of the electroconductive particle containing Examples 1 to 4 has high conductivity.

In addition, about L^*Value can be confirmed that in the film of Examples 1 to 4 that the aluminium powder of coated metal, which has, is better than comparative example 1 tone.This is considered following reason: coated metal is equably precipitated on Al powder.In addition, learnt by the result, about Electroconductive particle of the invention, in the case where its metal envelope includes Ag, L^*Value becomes 30 or more, and then becomes 40 or more. It is believed that the value be judge whether it is one of electroconductive particle of the invention will be because.

Embodiments of the present invention and embodiment are illustrated as described above, but initially having planned can be by above-mentioned each reality The composition for applying mode and embodiment is appropriately combined.

Being considered as embodiment and embodiment disclosed in this invention in all respects is to illustrate to describe and not restrictive. The scope of the present invention be not above explained part but by specific technical solution represented by, also include and this law technical solution Being had altered in equivalent meaning and range.

Claims

1. a kind of electroconductive particle, has: the core particle containing aluminium and the metal envelope for being coated the core particle, and institute Stating metal envelope has the electric conductivity for being higher than the core particle, and the metal envelope is 80% to core particle surface covering rate More than,

The L* value of the electroconductive particle is 40 or more,

The film thickness of the metal envelope is 10nm or more.

2. electroconductive particle as described in claim 1, wherein the average grain diameter of the core particle is 0.1 μm or more and 50 μm Below.

3. electroconductive particle as described in claim 1, wherein the metal envelope contain selected from by gold, silver, copper, nickel, platinum, At least one or more in group that palladium, tin, zinc, cobalt, chromium and their alloy are constituted.

4. electroconductive particle as described in claim 1, wherein be coated the amount of the metal envelope of the core particle in the conduction Property particle in be 1 mass % or more and 80 mass % or less.

5. a kind of conductive resin composition contains electroconductive particle according to any one of claims 1 to 4 as conductive Material.

6. a kind of coating material on matrix there is the conductive resin composition as described in claim 5 to be formed by film.

7. a kind of manufacturing method of electroconductive particle comprising following process:

In the process of core particle of the in the mixed solvent addition containing aluminium containing organic solvent and aqueous solvent；

In the process that the in the mixed solvent addition etchant containing the core particle is etched the core particle；And

Metal salt and reducing agent are further added in the mixed solvent, to form tool on the surface of the etched core particle There is the process of the metal envelope of the electric conductivity higher than the core particle,

The organic solvent contains at least one or more in alcohol series solvent, glycol ether series solvent and ketone series solvent.

8. the manufacturing method of electroconductive particle as claimed in claim 7, wherein in the process being etched and the shape In process at metal envelope, the volume ratio of the organic solvent of in the mixed solvent is 10% or more and 90% or less.

9. the manufacturing method of electroconductive particle as claimed in claim 7, wherein in the process for forming the metal envelope, The temperature of mixed solvent is adjusted to 0 DEG C or more and 60 DEG C or less.